Any Ford piston slap is a non-destructive problem. Unlike Chevy's problems with it.

There are inserts for the spark plug holes, that can be installed without pulling the head off the motor.

If you can get it cheap, DO IT! Get it home, do the plugs the RIGHT way (read the FAQ at the top of this forum) and be comfortable. If while you're in there, one of the plugs comes out with the aluminum threads stuck to it, fix it right away.

I don't think you can go wrong, if you need an SD's size and capabilities.

 

The V10 with the auto trans is one sweet set-up. You will not regret it!

 

If the truck looks like it is in good shape, and if the right price, I wouldn't count it out just because its a 99'. I have a 99' F250 with close to 120,000 miles on it and it runs like a top. I did have a plug blow out on me, and after it was all said and done, it wasn't all that expensive or hard to fix. Just keep the plugs torqued to 14 ft/lbs and all should be fine. I have never experienced any piston slap either in the 20,000 miles I have owned it. Overall its an excellent motor and truck

 

i have a 1999 ford f250 superduty with the 6.8l v10.it has 180,000 on it now. love the truck!!! never had a spark plug come out. never had a problem with piston slap. only problem ive had was spark plug boots rotting out, and a cracked flywheel. still running strong!!! love it!!!